Slice the tenderloin into 6 even sized pieces. Place each piece between a layer of plastic wrap and use a mallet to pound it out to 1/4 inch thickness.
Add the onion powder, garlic powder, salt, and pepper to a small bowl and stir to combine.
Season both sides of the pork.
For the breading:
Add the flour and seasoned salt to a second shallow dish and stir to combine.
Whisk the eggs and water together in a shallow dish.
Add the panko to a third shallow dish.
Dredge each piece of pork in first the flour, then egg, then panko, making sure the pork is fully coated in the breading.
For baking and serving:
Melt the butter and pour onto a large rimmed baking sheet.
Place each of the breaded tenderloins in the butter and bake for 8 minutes.
Flip and continue baking for 7 more minutes.
Serve on buns with the condiments of your choice.
Notes
These may also be fried on the stove in 1/4 inch of oil. We top our tenderloins with dill pickles, onion slices, and mustard.